The psychological assessment of subjects participating in clinical trials has become an important part of the section's research interest. An important finding in the past year was the association between Antisocial Personality Disorder and response to contingency management treatment. Over the course of the past two years we have been evaluating the effectiveness of voucher-based reinforcement contingency management procedures in producing sustained cocaine abstinence. Patients could exchange the vouchers for goods or services which were consonant with the development of a drug-free life style. The study was conducted in patients in a Methadone Maintenance treatment program who were consistent users of cocaine. Approximately 50 % of the patients assigned to the contingency management (experimental treatment) were abstinent for 7 weeks or longer over the course of the twelve week study. Patients who received the vouchers non-contingently (control treatment) showed continued cocaine use. Among the 56 patients who were exposed to the voucher-based contingency management procedures, eleven of patients met the DSM III R criteria for the diagnosis of Anti-Social Personality (ASP). Patients who met criteria for ASP achieved an average of 1.0 weeks of sustained cocaine abstinence; in contrast, patients who did not meet the criteria for ASP achieved an average of 6 weeks. It would thus appear that despite the clear-cut contingencies and immediate reinforcement for cocaine abstinence, ASP was a risk factor for treatment failure. Studies to improve drug use monitoring in clinical trials continue using qualitative urine toxicology and sweat patches. In procedural studies to identify improved outcome variable in clinical trials, the usefulness of quantitative urinalysis for cocaine metabolite and creatinine correction techniques and the relationship between these data and self-reported drug use were assessed with data collected in a clinical trial (N = 37) of a contingency management behavioral treatment intervention. Rules were developed to differentiate between occasions of new use and carry-over in positive qualitative urine tests. Preliminary analyses suggest: qualitative and quantitative urine testing show greater rates of drug use than that shown by self report; quantitative testing provides a means of differentiating incidences of new drug use from residual carry-over; the identification of new use with quantitative testing may help to reconcile differences between rates of drug use indicated by qualitative urine screens and self-report.